


Sinful

by SlendShady



Category: Ao no Exorcist | Blue Exorcist
Genre: Biting, Blood, Bottom!Yukio, I have no excuse for this, M/M, Okumuracest, Rough Sex, Scratching, Shameless Smut, Slight Crossdressing, Sorry Not Sorry, Top!Rin, frickle frackin in the classroom, just spent the past seven hours of my life disappointing jesus, yukio in thigh-highs
Language: English
Status: Completed
Published: 2017-06-01
Updated: 2017-06-01
Packaged: 2018-11-07 12:21:21
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 8,883
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11058870
Author URL: https://archiveofourown.org/users/SlendShady/pseuds/SlendShady
Summary: “I want you..”He heard the hitch in his twin’s breath.“I have always.. wanted you.”He neared his brother’s face, lips merely inches apart as hot breaths mingled against each other. His eyes were clouded, dark and heavy with lust and longing, once brilliant blue oceans now a dark abyss of temptation that drew Yukio in with ease.“And I know you want me too… don’t you..”





	Sinful

 

 

 

_“I wonder what I should cook for dinner later..”_

Rin stared out of the classroom window, chin resting in his palm as his mind drifted off towards anything other than the lecture he was supposed to be paying attention to. He couldn’t help it, really. Sitting in a chair and listening to someone talk for hours on end just really wasn’t his preferred way of learning. He needed hands on experience. He absorbed information so much better when he could touch and interact with things and situations. Not to mention, he had far too much energy to glued to a chair long enough to pay attention. His leg bounced under the desk impatiently as his brilliant blue eyes drifted over to the clock.

 _“Still 30 minutes left before break..”_ he thought.

He groaned inwardly to himself and leaned back in his chair slightly, turning his attention back to the window to gaze outside. Just as he began to mull over which manga issue he needed to read next, there was a very loud smack against his desk. The half demon’s tail shot straight up and the tuft end puffed out as his body jerked abruptly, reasonably startled, his heart hammering in his chest and his hands gripping the desk. Shooting a glare he stared up at whoever had the nerve to scare the daylights out of him. That glare very quickly dissolved however when he found irritated teal eyes staring down at him from behind a set of black rimmed glasses. His brother was shooting him a hard stare, holding a heavy textbook in hand which was most definitely the cause of the abrupt noise.

“Mr. Okumura, would you be so kind as to repeat to me what I just said..” He stated as he stared down at the blunette.

“Uhh..” Well.. **_shit_**. This was what he got for not paying attention. It always irritated him to no end that his brother would randomly call him out in the middle of class and make him look like an idiot. Yeah, he was the teacher, but Rin didn’t think that gave him an excuse to be an ass sometimes.

“Well..?” His brother prodded.

“I.. I don’t know. I wasn’t listening.” He was honest at least. There was really nothing else he could offer as an answer.

Yukio sighed, pushing the rim of his glasses up on the bridge of his nose. “See me after class.” With that he walked back to the front of the classroom.

Rin groaned audibly this time and leaned his head back. He knew that _“See me after class.”_ really meant _“I’m going to chew your ass out for not paying attention, again.”_

“Good job Okumura..” He heard Bon from a few chairs away.

“Ok seriously, like, literally no one asked for your input.” He growled in the back of his throat, shooting a glare at the other student.

Bon was about to retort before they both heard Yukio clear his throat rather loudly, looking up to him to see his raised eyebrows, silently scolding them for being disruptive. Both students conceded and remained silent for the rest of the class period, Rin combing his fingers gently through the puffed out tuft of his tail to smooth it back out.

Finally, after 20 more grueling minutes of listening to Yukio lecture about things Rin still wasn’t listening to, it was time to be dismissed for break. Before they were released his teacher spoke to them briefly about the assigned homework, walking around to each student to hand them said work. It was just then that Rin noticed something.. _off_ , about his brother’s attire. He looked him up and down, scanning him meticulously trying to figure out what it was. Then it dawned on him. His pants, or rather what little he could see of them thanks to his long exorcist coat, were different. He could only see a small section of them towards his ankles, and it sort of threw him off because it didn’t actually look like pants at all. Whatever fabric was covering his legs was skin tight against him, elastic.. maybe? They were black so it really didn’t stick out that much from his usual attire; not at all really unless you took the time to really stare at him.

Which Rin did quite often, actually. It was no secret to anyone that his twin was gifted in appearance. Broad shoulders, a well-built physique, lean but strong muscles, and a gorgeous face to boot.. It was no wonder he was surrounded by girls so often. Sure, maybe it was weird for him to think such things about his own brother, but he’d come to terms with his feelings a while ago. He was also pretty sure that his brother felt the same way.. at least a little, anyways. Every so often he’d catch Yukio’s eyes lingering on him longer than usual when he was changing in their dorm. He’d secretly see him raking his eyes over his figure when he got out of the shower with nothing but a towel wrapped around his waist. Once he even heard his brother softly panting his name in the middle of the night, and he was _PRETTY_ sure he’d been jacking off while he did. If that wasn’t a strong indication of his feelings towards Rin, he didn’t know what was.

He never said anything, though. He knew if he spoke up to Yukio about it his twin would probably deny it to Gehenna and back. He was a stubborn ass like that. So even though neither of them ever verbally expressed their desired feelings, they did drop subtle hints. A little brush of the skin here, a bit of a longing gaze there, you know, things like that. The attraction was left unspoken, but it was definitely there.

The half demon slipped out of his thoughts momentarily to stare back at the weird clothing peeking out from under his brother’s coat. Maybe they were some of those elastic workout pants.. he’d heard his brother complain about the pants of the exorcist uniform not being flexible enough sometimes on missions. It would make sense that he’d switch to something more moveable, he guessed. He also wasn’t really sure why he was so curious about his brother’s choice of clothing, suddenly questioning himself for even pondering on the subject. It was just.. so _weird_ to see Yukio deviate from his norm. It was unusual, so naturally, he questioned it.

 _“I wonder if those are like… yoga pants are something..”_ He thought.

Suddenly the image of his brother’s firm yet surprisingly well-rounded ass squeezed into a form-fitting pair of yoga pants popped into his mind.

 _“Oh hell.. bad idea.. nope nope nope back up Rin.”_ He mentally tried to pull himself out of the rabbit hole his thoughts were about to descend into. _“The last thing I need is a boner in class..”_

He willed himself to close his eyes and take in a deep breath, holding it before slowly releasing in an attempt to calm his hormones. Suddenly he heard someone clear their throat and looked up to see Yukio holding a paper out to him, looking mildly miffed, again. Rin looked off to the side to avoid his gaze, taking the paper before Yukio returned to his own desk to finally dismiss everyone. They all gathered their things and took their leave for the 30 minute break. All except for Rin, who stayed right where he was and prepared for the thorough bitching he was about to receive from his brother. Once everyone else had left, Yukio looked up at Rin with a stern frown.

“Come here..” He said with a sigh.

Rolling his eyes, the blunette stood up from his seat and dragged his feet over to his brother’s desk, leaning up against it as he waited for the lecture to ensue.

“Rin.. how many times do I have to have this talk with you before it finally sinks in.” He sounded more exhausted than angry.

“How many times do I have to tell **_you_** I just can’t concentrate in a classroom. You KNOW I do much better hands on than I do listening to someone drawl on for hours.” Rin retorted.

Yukio sighed and leaned back to rub the bridge of his nose. “Rin, as much as I’m sure hands on would be a more effect way to teach you, that’s simply not an option here. You HAVE to do well in class as well as out in the field and you KNOW that the Vatican is keeping a close eye on you concerning this..” He furrowed his brow, trying to get it through his brother’s thick skull how important this was.

“Yeah well the Vatican can kiss my..” he stopped when he saw the look his brother was giving him. “Look.. I know, I know it’s important and shit for me to do well.. but it’s hard! I don’t have the attention span for this crap. Do you know how boring it is to sit in one spot for hours and listen to somebody talk _AT_ you. Not even _TO_ you. _**AT you**._ ”

“Yes, Rin, I do. You know it wouldn’t be so boring if you actually listened. You could learn some really interesting things.. not to mention important lessons that could save your life or someone else’s on the field..”

“You are such a nerd I swear..” Rin huffed and looked the other way.

“Rin..” he reached out and grabbed his brother’s arm, gently, but squeezing just enough to demand his attention. “Please.. Just try a little harder? Actually apply yourself in class for once?”

The blunette sighed and looked back at his brother. It wasn’t fair when Yukio said _“please”,_ because he couldn’t find it in him to defy him. He put a hand over his brother’s and squeezed gently. “Alright.. Alright. I’ll try a little harder.” He said it almost mockingly, but he meant it. He was just irritated to be giving in to his twin.

A small smirk graced Yukio’s lips. “Thanks.”

The brothers let go of each other and Rin gathered up his bag and his sword, slinging both over his back.

“I’m gonna go each lunch, you wanna come with, or..?” He trailed off, looking at all the papers on Yukio’s desk.

“I’ll have to pass, I have some work that I need to get done. Thanks though.” He offered a small smile to Rin, who shrugged and smiled back as he turned towards the door.

“Alright! See ya after break then.” He hummed and turned out the door, beginning his trek down the long hallway.

He only made it about halfway down the long hall before he suddenly remembered something. He’d made Yukio a bento for lunch! He nearly forgot as he reached into a bag and pulled out the small parcel with his twin’s meal in it. Well shit, he needed to go back real quick and give it to him. Even if he couldn’t come eat with Rin, he could at least have something to eat while he worked at his desk. Rin turned on his heel and walked back to the classroom. Slowly he opened the door, absentmindedly speaking.

“Hey Yukio! I almost completely forgot I made a bento for you so you can- _Oh. My. **God**_ **.** ” He froze when he finally looked up at his brother.

Yukio was standing against one of the desks, bent over and tending to something attached to his thigh. His right leg was straightened and propped out with the opening of his exorcist coat pulled back to expose the appendage. In his hands was the elastic band of the top of the _STOCKINGS_ he was wearing.

He wasn’t wearing yoga pants.

He was wearing black. Satin. Thigh-high. Stockings.

Fucking.

**_Stockings._ **

He’d been adjusting the annoying elastic band around his thigh that had rolled down and bunched up during his lecture just has his brother walked through the door… and he wanted to **_die_**.

At that very moment he wished Satan himself would appear and drag down him into Gehenna so he wouldn’t have to face the mortification of his brother finding out that under his exorcist coat he was wearing fucking **_stockings_.**

Quickly he pulled his exorcist coat back down over his leg to cover it, standing up straight and staring at his brother with a quickly reddening face. Neither of them said anything for what felt like forever as they both stood frozen in time, staring at each other. Rin was having a very hard time processing what he’d just witnessed. _His brother, Yukio, wearing thigh-highs._ His head started to spin with question after question.

_How long had his brother been into wearing women’s clothing? Why had he never noticed this before? Did he do it because it was comfy? Did he get some kind of secret kick out of it? How often did he walk around secretly wearing such things? What else-_

His breath hitched in his throat suddenly..

_What else does he like to wear under his uniform..?_

It didn’t take much for Rin’s mind to suddenly become clouded with images of Yukio wearing nothing but stockings. Those lithe, well-muscled legs tightly hugged by smooth black satin, the top band of those stockings clinging to those thick thighs.. **_fuck_**. The blunette found himself suddenly hungry, but not for the bento in his backpack.. His core slowly began to burn and crave for something he knew he shouldn’t. A low, deep growl rumbled in the back of his throat unintentionally. As if suddenly snapped out of his daze by the sound, Yukio took a step back.

“Rin.. It’s not.. wh-what you think.” Fuck him, he was stuttering and making an idiot out of himself.

Rin didn’t really seem to pay any mind to his words as he closed the door behind himself, never taking his eyes off his brother. Slowly he strode towards his twin, a glint in his eyes that was unidentifiable, but concerning.

“Rin..” he spoke with a warning in his tone, unsure of what his brother was doing, much less thinking. He backed up against the desk even more and cursed it for existing at that very moment, keeping him from backing away further.

The half demon walked up to his brother and stared into his eyes for a moment, silent, before dropping to a kneel to stare at the lower half of the long exorcist coat that was blocking his view.

“Lemme see.”

“What..?” Yukio was surprised at the question.

“I said lemme see.” Rin looked up at his brother and reached a hand out to try and tug the coat up.

“Wha- No! Hey!” He smacked his brother’s hand away and moved to press his coat tightly against his legs to prevent Rin from messing with it, growling lowly at him, though unintentionally.

Rin huffed up at him, frustrated at his brother’s stubbornness. The least he could do is let his twin have a peek, considering he’d hid this dirty little secret from him for who knows how long. Suddenly, a grin passed over his lips as he stared up at Yukio, finding his red cheeks and ears undeniably amusing. It wasn’t often he got to see him flustered like this.

“So.. when were you gonna tell me you like wearing women’s clothes..?” He asked as he absentmindedly toyed with the bottom edge of the exorcist coat.

Yukio huffed with embarrassment at the question and moved his coat away from his brother. “Never! It’s none of your business what I like to wear!” He could feel his face getting redder with each passing second.

“It’s not even a little bit of my business..?” he mused. “I mean.. we **_ARE_ ** twins.. and we’re basically attached at the hip.. so.. “ He grinned at his twin even more.

“Being twins does NOT mean I have to share every aspect of my private life with you!” He finally gathered his wits enough to stride around his brother and make his way to his own desk, standing with his back turned to the older as he rather sporadically began to sort through his papers, hoping and practically praying that Rin would drop the subject.

His prayers went unanswered.

The blunette hummed as he stood back up and walked over to the glasses-clad brunette, standing behind him for a few moments, silent, pondering. Yukio felt his presence behind him and it made him uneasy. More specifically, it was his brother’s unusual silence that made him uneasy.

“Please don’t just linger, Rin, it’s weird. You should probably go eat lunch while you still have ti-“

He was abruptly cut off by a strong hand wrapping around the back of his neck and forcing his upper body down against his desk. It wasn’t hard enough to hurt him, but certainly firm enough to hold him in place.

“R-Rin!!” He nearly squeaked, the side of his face pressed against the hard surface as he looked back at his twin over his shoulder. He felt his feet being kicked apart so his legs were spread. Desperately he tried to push back up off the desk and move his legs back, but the strong hand against his nape kept him pinned as it gripped harder, his legs pinned in place as his brother’s knees dug in against them. His heart hammered in his chest as his mind frantically tried to reason with his brother’s actions.

“Rin! What are you doing knock it off!” he shouted back, but his words didn’t seem to do much. Neither did his tail which had uncurled from its hiding spot in his coat to swat at his brother’s side.

“Oh hush.. I’m not hurting you. I just wanna look. What’s wrong with that?” he asked honestly, peering into those teal eyes that stared back at him with a mixture of anger and confusion and.. something else.

Yukio turned his eyes away from the blunette and reasoned with himself. Maybe if he just sucked it up and let Rin look, he’d leave him alone. He hoped anyways. Considering his current situation he didn’t really have any other options. It was clear Rin wasn’t going to let up his grip until he gave in.

He sighed and looked back at his twin. “Fine.. but make it quick please, I seriously have stuff to do..” He tried to sound firm about it, but he couldn’t help the slight quiver in his voice.

“Yeah yeah..” The demon boy said absentmindedly.

Slowly he relinquished his grip on his brother’s neck in favor of leaning down slightly to tug at the opening slit of the coat, gently pulling it up and off to the side to expose that gorgeous leg that was covered in satin. Just as he pulled it up to the underside of his brother’s ass Yukio lifted his torso and looked back at him with urgency.

“Hey you pulled it up far enough!” he sounded slightly panicked, not terribly comfortable with how exposed he was already.

Rin conceded and put his hands up. “Alright alright, don’t freak.”

Deep blue eyes roamed over the expanse of his twin’s well-toned legs, admiring every ripple of muscle beneath the slightly shiny fabric. He turned his attention to where the top band of it hugged the middle of his thigh, feeling that warmth in his gut grow hotter. He stole a brief glance up at his brother’s face to see that he was turned away, seemingly trying to ignore his twin’s ministrations.

_Well.. that’s no fun.. now is it?_

With a grin he kneeled down behind the brunette, making the other look back over his shoulder in surprise.

“What are yo-“ He cut himself off with an unexpected gasp as he felt Rin press a hot, open mouthed kiss against the back of his thigh just above the band of his stockings and right under his ass.

The younger slapped his hand over his mouth, mortified at the sound he’d just made. He felt the other grin against his skin, opening his mouth again to graze his pointed teeth over the sensitive spot as he dragged his tongue across his flesh. Yukio leaned forward on his desk, resting on his elbows as his hand stayed clamped over his mouth, trying, and failing, to suppress the surprised noises spilling from his lips. He couldn’t help the quiver that his legs gave, hearing a chuckle come from the blunette behind him. His tail even subconsciously draped over the back of his twin’s neck as if to encourage him forward.

“You’re really loving this.. aren’t you?” Rin asked with a low, seductive growl in the back of his throat, grasping the elastic band of the stocking and pulling it back so it snapped against that muscular thigh.

He grinned wider when he heard the younger gasp above him. He waited for an answer, expecting his twin to throw a flustered fit, but when he got no response, he hummed. Reaching down, he laid his palm against the brunette’s lower calf, giving it a gentle squeeze as he slid his hand up, traveling over that expanse of black fabric up to his outer thigh, again giving a squeeze. He heard a few muffled noises, but nothing more than that. It was as if his brother was just trying to pretend he wasn’t there, but like **_hell_ ** was he going to be ignored. He grabbed the coat once again and started to pull it even further up, hiking it up over his brother’s backside, which certainly got his attention.

“R-Rin no I said don’t-!” He looked back with a panicked expression and tried to push himself off the desk, but again that strong hand pinned him down by his nape before he could escape. He stared back at the half demon who’s expression was surprisingly.. surprised.

“You have **_got_ ** to be fucking kidding me..” Rin grinned smugly, his voice filled with utter amusement as he stared down at the backside he’d just revealed.

Apparently, Yukio had a thing for women’s underwear as well.

Adorning that toned backside was a pair of matching black satin panties, cut in the style that let the bottom of his ass cheeks peek out just enough to be a complete tease. It was such a lewd and tantalizing sight to take in. His brother wearing panties and stockings, bent over his desk and staring back at him with wide eyes and flushed cheeks.. just.. **_fuck_**.

That was exactly what he wanted to do to his twin.

“You know.. I thought the stockings alone were pretty hot..”

He spoke absentmindedly, making his brother’s breath hitch in his throat as he continued.

“But this..? Now this is fucking **_sexy_**..”

He emphasized his last statement by grabbing a handful of that fabric that hugged his backside and pulling up on it, stretching it taught against that gorgeous ass, lewdly outlining the brunette’s balls and exposing even more of his cheeks as the fabric was stretched, leaving little to the imagination. A growl rumbled in the back of his throat as he soaked in that image splayed out before him, storing that precious memory away for later. He let go of his brother’s underwear and leaned forward; pressing his strong chest against the younger’s back, brushing his lips delicately against his pointed ear.

“Yukio..” His whisper was rough and dripping with need. Languidly he rolled his hips forward, pressing his clothed but obvious erection against his brother’s backside, earning a gasp from the other.

“Rin.. we s-shouldn’t..” He tried to be firm with his tone but it just wasn’t working. His body yearned for his brother’s touch and he was all too aware of that, no matter how wrong it was. He gasped quietly as he felt the other press an open-mouthed kiss against the side of his neck, grazing his fangs over that sensitive spot and making him emit an unintentional whine.

“Why shouldn’t we..?”

The blunette mumbled between pressing kisses against his brother’s neck.

“Because it’s wrong..?”

He panted and dragged his tongue across his brother’s neck up to his ear.

“Because it’s **_sinful_**..?”

He purred with a low growl against the shell of the brunette’s ear, feeling the body beneath him shudder as he gently nipped at it.

“I don’t care how wrong it’s supposed to be..”

His hand slid from the back of his brother’s neck, caressing its way around to the underside of his jaw where he gripped firmly, but gently as he turned Yukio’s head to the side to force him to look into his eyes.

“ ** _I want you_**..”

He heard the hitch in his twin’s breath.

“I have always.. **_wanted you_**.”

He neared his brother’s face, lips merely inches apart as hot breaths mingled against each other. His eyes were clouded, dark and heavy with lust and longing, once brilliant blue oceans now a dark abyss of temptation that drew Yukio in with ease.

“And I know you want me too… **_don’t you_**..” 

It was more a statement than it was a question, but still he waited for a response. He expected his twin to deny him, to say he was crazy and try to pry from his grip. He expected him to have a complete fit and to tell him to leave.

What he didn’t expect was for the brunette to surge forward and press his lips against him.

But he wasn’t complaining..

Immediately Rin reacted to the kiss, threading his fingers through that soft brunette hair as his tongue swiped over the younger’s lips, asking for entrance. He was quickly granted the access he so desired, swiftly pushing his tongue into that hot, eager cavern, licking and tasting every surface he could reach slowly and sensually, earning a muffled moan from the other. Together their tongues danced against one another, heated breaths mixing and soft moans melding against flesh. Yukio dragged his tongue across his brother’s canines, daring to brush against their pointed ends, subconsciously fascinated with the demon like features, despite having his own. Rin certainly didn’t mind. In fact, it excited him that his counterpart was enamored with his demon-like traits, and he fully intended to use that fascination to his advantage. Breaking the kiss he pulled his head back, staring at the flushed face of his brother, both of them panting heavily for air. The fingers that were threaded through Yukio’s hair suddenly tightened, gripping firmly as they pulled his head back, forcing the younger’s neck to arch back and expose that perfectly un-marked skin. The half demon was surprisingly amused to hear a moan sounding from the other’s throat in response to having his hair pulled.

“You like that huh?” He grinned as Yukio stared at him with pleading eyes, giving another experimental tug and being promptly rewarded with another low moan.

_Good.._

Suddenly the blunette leaned forward, latching his mouth onto the side of the exposed throat before him. He growled in a deep, rumbling tone, one that dripped with the need for possession and dominance. Those sharp canines teasingly dragged over the expanse of skin beneath them, finding a certain tender spot and biting down against it.

Yukio gasped sharply as he felt the sting of fangs sinking into his neck, wrenching his eyes shut, panting as the strange sensation of pain mixed with pleasure shot through his nerves like a bolt of lightning straight to his groin. He was being marked, claimed by his older twin in such a feral way and.. _fuck_.. he _loved_ it. He felt the last of his resistance slowly crumble away with that one bite, finally relaxing his body and melting into his brother’s grip, pressing his neck further into that sharp bite as he let out a loud, unrestrained moan. Finally he was giving into the sinful desires his body craved and relinquishing his control over to the blunette, something that was entirely foreign to him. Normally he hated not being the one in control. Being in control made him feel secure, safe even.. But in that moment, with his brother’s strong arms wrapped around him, holding him as he licked the blood away from his neck and kissed where he had bitten in silent apology, Yukio finally let go of his control, so he could fall apart into bliss beneath him.

“Rin.. please..” He pleaded to him in a breathy tone, reaching up to gently cup the half demon’s jaw in his palm, staring into those deep blue orbs as he leaned up to press his lips against him again, tasting copper against his tongue as he swiped it over the other’s mouth.

“Claim me..” He whispered.

And that was all the encouragement Rin needed.

He released a deep guttural growl in response, his core heating and twisting almost uncomfortably. He knew what his brother wanted.. that his request was not simply him asking to be fucked. He was asking Rin to **_take_** him, to mark him as his own. He wasn’t just asking for Rin, he was **_submitting himself to Rin_.** He was offering himself up to his brother, exposing himself in the most vulnerable of ways, both emotionally and physically, and the blunette was more than happy to take anything and everything his brother was giving to him.

Suddenly, strong hands were pulling against Yukio’s shoulders, making him stand up straight before moving to the buttons on his exorcist coat, making quick work of each one. Those sharp teeth found his neck again, this time sinking into his nape and making him arch back, gasping his twin’s name as his body shuddered.

“Coat.. off.. now..” Rin muttered against his bloodied nape, licking at the wound he’d caused with care as he grabbed at the heavy coat and helped to pull it off of his brother’s shoulders.

The brunette shrugged the heavy clothing off of his body, letting it fall to the floor with a muted thud, left clad in only his white button-up and the satin garments that had spurred this entire situation. It wasn’t enough though. The demon boy wanted more.. _needed_ more of his brother’s gorgeous body exposed to him so he could mark him. He wanted to feel that soft, bare skin against him. In a sort of rushed fit he quickly pulled his own shirt up over his head, tossing it aside before reaching around to the front of Yukio’s shirt. He didn’t even care to waste time on the buttons, simply tearing it open and earning a surprised gasp from the other, no doubt breaking a few buttons off in the process. He didn’t stop though, yanking the offending fabric down off of his shoulders so that it hung loosely from his brother’s arms. Reaching around with one arm he grasped at Yukio’s neck just beneath his jaw, his other arm coming to wrap around his torso, pressing firmly into his abdomen to pull him back against the blunette’s bared chest. They both groaned at the sudden contact of bare skin against skin, the sensation of friction and heat making them dizzy for a brief moment. Rin gripped his brother’s throat firmly and angled it off to the side, lapping at the junction of his neck and shoulder before yet again sinking his fangs into that delicious flesh. He couldn’t get enough of the sensation, ruining his twin’s perfect skin with possessive bite marks, tasting the oddly sweet copper against his tongue each time he bit down, hearing his brother moan for him as he sank further into submission.. It was absolutely _intoxicating_. He felt that toned abdomen twitch beneath his fingers as he pressed his claws into it gently, just enough to scratch and leave behind light red trails as he dragged his hand across the expanse of his twin’s midsection, earning a shudder in response.

“Rin..” He sounded choked, desperate. “Please.. more..”

The blunette groaned and rolled his hips up against his brother’s ass, removing his hands and placing them against his shoulder blades, pushing Yukio down so his torso rested against the desk, leaving that gorgeous rear end raised in the air.

“Fuck..” Rin panted out as he raked his claws down his back, leaning over to bite at his side, making the other choke out a strangled sound of pain and pleasure. “ ** _Mine_**..” he growled against the tender flesh against his lips.

Without skipping a beat he dropped to his knees behind the younger and pressed his open mouth directly against the lewd outline of his balls straining against the tight underwear, mouthing against the sensitive area through the fabric as he squeezed his thighs in his hands.

“Ohmyg- R-Rin-!” Yukio gasped out and clenched the desk in a white knuckled grip. “Oh.. g-god yes..” He panted and pressed himself back against the older, practically begging him for more.

The half demon growled against him and reached up to grasp the waistband of the satin underwear, swiftly yanking it down around his thighs in one eager motion, hearing his brother gasp at the sudden rush of cold air that hit his intimate regions. He grinned and stared at the now bare skin in front of him, licking his bloodied canines as he eyed the meaty flesh of that rounded ass. Leaning forward he pressed a kiss against the back of his twin’s thigh, trailing kisses and licks up to his firm cheek before biting into it, this time earning a yelp in response. The blunette grinned against the wound and dragged his tongue over it before turning his attention to his intended goal, grasping both cheeks of the other’s rump in each hand and lewdly spreading them apart. He exhaled a heated sigh against the tight ring of muscle just in front of his face and delighted in the gasp that rose from his brother.

Yukio was falling apart with every touch, kiss, and bite that his twin lavished him with, slowly but surely drowning his senses in absolute lust and ecstasy. Suddenly, there was a hot, wet tongue dragging across his entrance, the sensation wrenching a husky moan from his lungs as his hips bucked backwards automatically, desperate for more. Apparently his brother caught onto the hint because soon that wonderful tongue was pushing into him, licking and forcing its way past that tight ring, causing Yukio to push himself up on his elbows on the desk and throw his head back in a long, drawn out moan.

“Fu-.. oh my go-d.. R-Rin _yes_ -! M-More..” He panted and shoved his hips back even harder in a desperate attempt to push that tongue in even deeper, inadvertently rocking himself back against his brother’s mouth as he ate him out, his tail even pulling against the back of his neck to urge him on.

 _“Ask and you shall receive..”_ The blunette thought with amusement as he pulled his head back, grinning at the whimper that came from the other at the loss of contact. He pondered mentioning that his brother had nearly cursed out loud, but decided to save his comment for later. “Don’t whine.. I’m far from done with you..”

He rumbled out with another growl as he brought his fingers up to his mouth, thoroughly wetting and slicking them up. Once he was satisfied he pressed his index finger against the tight ring of muscle, teasing it for a moment before easing his finger inside in one fluid motion. He heard the hitch of his twin’s breath and felt him tense up at the sensation, feeling both slight pain and pleasure. In an attempt to relieve some of the brunette’s tension he reached his hand in between the other’s legs and grasped the straining cock he’d been ignoring up until now, making him keen in pleasure. Sure, he wanted to fuck the absolute shit out of Yukio as soon as possible, but he was still aware enough of his actions to make sure he didn’t hurt him. As possessive and borderline animalistic as he was being, he still wanted this to be pleasurable for the both of them, not just himself. Slowly he stroked the thick cock in his hand as he wriggled his index finger around in that tight heat, stretching and prodding around inside until it was loosened up enough. His middle finger slowly joined in, pausing at the first knuckle when he felt the muscles tensing up around them, a pained hitch sounding from his twin. He waited for his brother to relax, gently pressing his thumb against the slit of his cock as he squeezed around the head, his mouth occupying itself by pressing opened-mouth kisses against the back of his thigh. He took the satisfied sigh from above as his cue to continue, slowly pressing his middle finger inside, coaxing a low groan from the brunette as he began to scissor his fingers and stretch him more, pressing and prodding around those inner muscles until he pressed against something that had his brother choking on his own breath, body going rigid as he nearly screamed.

“Th-there! R-Rin ohgod.. right there-!” He cried out to his twin as his own claws dug into the desk, scratching grooves into the surface.

Rin smiled and pushed even harder against that spot, relishing in the desperate cries that were falling from his brother’s lips. He continued to assault that spot as he stretched those tight muscles, slowly adding a third finger to the group. The brunette didn’t even so much as tense up at the third being added, too far gone in his haze of pleasure, rocking his hips back against those fingers almost feverishly as the heat in his gut twisted and grew.

“I’m.. Rin I’m gon-na.. **_god_**.. I’m gonna c-cum if you don’t.. s-stop-!” He stuttered out between moans, quivering as he neared his limit. He didn’t want to cum yet though, not until his brother was inside of him.

The blunette halted his assault on his brother’s prostate, slowly sliding his fingers out and releasing his dick from his other hand, hearing the other sigh shakily. He rumbled in a soft growl to himself as he put those fingers in his mouth, again messily dragging his tongue over them until saliva was dripping down his hand. With his other hand he reached down and tugged at his pants and boxers, pushing them down to finally relieve his aching cock. He hissed as he finally freed it from its confines, grasping it with his saliva covered hand as he stood back up, shuddering as he spread that slick wetness over the length of it. When he was satisfied with his work he gripped Yukio’s hips and slid his cock against the crease of his ass, teasingly rutting up against him with a groan as he listened to the other gasp.

“Tell me what you want, brother..” he rumbled with a deep, commanding growl.

“Ahn.. R-Rin please…” He choked out as he dug his claws deeper into the wood he was laying against.

“Please what..?” He spoke as he rutted against his brother again.

“Ah-! F-Fuck.. F-uck me Rin.. Claim me and fuck me h-ard!” He gasped out heavily as he looked back at the blunette over his shoulder, emphasizing his desire by pushing his ass back against the cock pressing against him, making his twin hiss and grip his hips tighter.

“Fuck… good boy..” He dropped his mouth open, baring his fangs slightly as he lined himself up with that twitching entrance, slowly leaning forward to push past that tight ring, hearing Yukio utter a broken gasp.

He paused at the halfway point, panting and groaning at that tight heat that wrapped around his length as he gave his brother a moment to adjust, having felt him tense beneath him. Everything in him screamed to just _go for it_ , but he silently willed himself to be still, not wanting to badly hurt Yukio. Gently he rubbed a thumb against the base of his twin’s tail in an effort to relax his quivering figure, hearing him gasp for ragged breaths.

It took a moment for the initial pain to subside enough for the brunette to relax, slowing his breaths as he gave his hips an experimental thrust back, letting his brother know he was alright now. His claws raked deep grooves into the desk as the rest of that thick cock filled him to the brim, arching his back into a delicious curve with a needy moan. He felt that thickness suddenly leave him as Rin pulled his hips back, only to snap them forward again with an audible slap, practically forcing the air out of Yukio’s lungs in a breathy scream. It didn’t take long for them to find the rhythm they desired, hard and fast they moved in tandem, the younger pushing his hips back to meet every thrust. The room was filled with the sound of skin slapping against skin and the wanton moans and growls of both brothers.

In an attempt to find more leverage, Rin reached forward and grabbed a handful of that soft brunette hair, harshly yanking back on it to pull the younger back against him even harder. Yukio practically screamed out in ecstasy at the rough treatment, forcing his neck to crane up as his brother wrenched back on his hair while he fucked him into the desk.

“You really like that..?” He panted and grinned as he pulled hard again, hearing the other scream again. “You little slut..” He growled with amusement.

“A-ahhh! F-fuck, yes yes **_Y-ES_ -!!** G-od yes **_fuck me harder-!!_** ” He panted and gasped desperately.

That desperate plea was just enough to snap what was left of Rin’s self-restraint. Roughly he yanked back on his brother’s hair, pulling him up so that he was no longer leaning down against his elbows and instead his arms were outstretched straight, hands bracing against the desk. His ass was still arched out behind him, this angle causing the brunette’s spine to bow into a tantalizing curve as his lower abdomen pressed against the edge of the hard surface, his head tilted back so he was facing the ceiling. The blunette pulled on his hair and leaned forward so that the younger’s neck was level with his face. He bit down harshly, sinking his teeth into smooth skin as blood welled up in his mouth, simultaneously thrusting his hips up even faster, still using the hair in his grip for better leverage and added force. He held onto his brother’s neck with his teeth as he fucked him with inhuman power and speed, reveling in the screams that echoed off the walls in response. The tension coiling in his abdomen was dangerously close to bursting as he pulled his teeth away from his brother to seethe a hiss against his ear, never stopping or slowing his thrusts.

“Fuck.. who’s my good little slut..? Tell me who you belong to.. and I will make you cum harder than you ever have before..” He growled and bit at the pointed ear.

“I.. I-I am..” He was struggling to get words out at this point.

“You are _what?_ ” He hissed demandingly.

“I.. f-uck.. I-I’m yo-ours.. _ahhh-!!_ I’m yo-ur little.. s-slut-!! Oh _**f-UCK!!** ” _He barely managed to gasp the words out past his cries of ecstasy.

“Good.. don’t you _ever_ forget that..” He whispered almost threateningly.

Angling his hips slightly he slammed up against his brother’s prostate, grinning as he watched his twin’s mouth fall open in a silent scream. Relentlessly he thrusted against that spot, reaching around to grasp his twin’s leaking cock. It only took a few quick jerks and a few more thrusts against that sensitive bundle of nerves before Yukio was reeling in pleasure, his orgasm hitting him like a ton of bricks, practically knocking the air out of him as he came hard against the side of the desk, stuttering out broken and shaking gasps. Rin winced as the walls around his length tightened, squeezing him and pushing him to his own completion. He gasped and snarled, biting into the brunette’s shoulder blade as his hips stuttered, gripping him tightly as he came inside of that tight cavern, thrusting still and riding out his orgasm until he finally slowed to a stop, still buried deep inside of his brother.

Both of them quivered with exhaustion, still trying to come down from their post-coital highs. Their bodies were coated in sweat and smeared slightly with blood from all of the scratches and bite wounds. Once their highs passed and their bodies relaxed, Yukio practically fell against his desk in exhaustion, Rin’s hold on him being the only thing keeping him from falling over completely. He felt absolutely _wrecked_ , inside and out. His body ached and he was finally beginning to feel the sting of some of those scratches and bites. Strangely enough though, he rather enjoyed it. He enjoyed the sensation of being so wrecked and ravished that his body gave out. It was as if all the tension that had been building in him over the years was suddenly released and he was left in a state of calm, relaxed exhaustion. He winced a bit as his brother moved to pull out of him, only then realizing his brother was still biting his shoulder blade.

“Rin..” He panted. “You can stop biting me now… that kinda stings.”

Quickly his brother let go, muttering a soft apology, not having realized he was still biting him. He pressed gentle kisses against the wound and tenderly licked the blood away before sighing and resting his forehead against the brunette’s spine.

“That was… **_fuck_**..” The blunette’s voice was rough and tired, unable to find the right words.

Yukio made a slight noise of amusement. “Yeah.. it was.”

A few moments passed, the only sound between the two being their labored breaths.

“… Do you regret it?” Rin suddenly asked, hesitation in his voice.

Yukio was slightly thrown off by the question, shakily pushing himself up on his elbows to look over his shoulder at his brother. He looked.. nervous? Uneasy? The brunette pushed himself up more, and with much effort managed to turn himself around to face his twin, leaning back against the desk. He reached out to the other and quickly pulled him flush against his chest, pressing his lips against Rin’s in a surprisingly gentle, chaste kiss. When he pulled back he stared at those beautiful ocean colored eyes and just smiled ever so slightly.

“No.. Why would I ever regret that..?”

The blunette bit on his lower lip. “Because.. it’s supposed to be wrong..? I guess..” He sounded unsure of himself.

“Do **_you_** regret it?” The brunette mused.

“N-No! Of course I don’t! That was.. amazing.. I would never-“

“Then what are you stressing over?” He cut him off, smiling gently.

“I guess.. I mean.. I’ve always, you know.. wanted this.. with us. Wanted you..” His cheeks and ears began to turn red as his eyed diverted off to the side.

His attention was suddenly brought back when he heard his twin chuckling, slowly getting louder until he was actually laughing.

“H-Hey why are you laughing, I’m being serious!” He blushed even more, confused by his brother’s response.

Suddenly strong arms were pulling him in close again, holding him tightly as the younger continued to chuckle.

“After everything we just did, and **_NOW_** you are a flustered mess.. You are so weird.” He smiled against his twin’s hair. Just before Rin could say anything he spoke up again. “If I didn’t want you, I would have never allowed this to happen. I’ve wanted this too Rin.. wanted you. I just never acted on it because at first, I did think it was wrong. It scared me, honestly; how I felt about you. But at this point, I can’t say I care anymore. Holding you feels right.. kissing you feels right.. This is what I want.”

He pulled back a bit to look at his brother, who seemed to be stunned into silence, letting his brother’s words sink in. Finally, that bright smile slowly appeared on the blunette’s face as he leaned forward to capture Yukio’s lips in another kiss. They both smiled against each other, kissing until they were breathless again and needed to pull back for air. The brunette grinned and leaned forward to bury his face into the crook of his older brother’s neck, making him yelp with a groan as he bit down, leaving a deep, vibrant bite mark against his skin with a smirk.

“That.. is payback for biting me so much.. and to remind you that you belong to me as well.”

Rin blushed again, feeling joy well up in his chest as he smiled. “I think I can live with that..”

“Good.” Yukio chuckled and leaned against him, sighing with content as they held each other in complacent silence.

 

 

**_Until they heard the distant muffled sounds of people nearing the door._ **

Their hearts sank deep into the pits of their stomachs, both heads whipping around to look at the clock.

Break was over.

_Everyone was coming back._

**_Fuck._ **

Quickly, as though Satan had lit a blazing fire under his ass, Rin pulled back and lunged for the shirt he’d thrown on the floor earlier. He pulled it on in a frenzied panic, leaving Yukio to desperately grasp at the desk just to keep himself up. There was no way in **_hell_ ** he was going to be able to teach the second half of his lecture like this. It just wasn’t going to happen. They needed to think of something quick, and quick as in the next 10 seconds **_quick_**.

“Rin cut them off at the door or something!!” He spoke hurriedly as he managed to bend over to grab his exorcist coat.

“And say what?!” he was already jogging towards the door, awkwardly attempting to zip his pants up in the process.

“I don’t know just make something up!! You do it all the time!”

The blunette stopped just before the door, briefly enough to scoff as he feigned offense. “I do not!”

“ ** _RIN!!!_** ” The younger panicked.

The older grabbed the door swiftly and pulled it open to a crack just in time to see the other exwires outside of the door, looking at him with a bit of confusion.

“Why are you already here, Okumura?” Bon asked.

“Uhh.. w-well..” He wracked his brain, trying to think of something, anything he could throw out as an excuse for them to not come inside. “Uhhm, Y-Yukio called me here because.. he said he wasn’t feeling very well! Yeah.”

The other exwires looked at him a bit skeptically, all except for Shiemi who of course jumped straight to concern.

“Oh no is he going to be okay? How bad is it? M-Maybe I can help-“

“ ** _NO!!_** ” He accidentally shouted, catching the others off guard. “ No.. no it’s uhh, it’s alright Shiemi, I have it under control. Thanks though.” He offered her an apologetic smile.

“So does this mean we get to go home early?” Shima sounded excited.

“Uh.. yeah! I’m sure he’ll be better tomorrow!” Rin shot them all a goofy smile.

“Alright I guess… uh, by the way.. is there a reason your shirt is on backwards, Okumura?” Bon questioned as he raised a brow.

Nothing was said for a short few moments as the half demon’s face paled slightly.

“I just like wearing it this way sometimes!” He practically yelled, and with that, he closed the door and locked it, leaving the very confused exwires to stare at the locked entryway.

Bon opened his mouth as if to say something, but paused and closed it in favor of silence, turning on a heel to walk away. The others just blinked and turned to follow.

“H-Hey Bon, wait! Don’t you think Rin is acting kinda strange? Should we maybe go back and check on them?” Konekomaru spoke up.

“Nope. I don’t wanna know. I’m going home.” Bon replied.

Back in the classroom, Rin leaned his back against the door and sighed heavily, running his hands through his hair. When he looked up he noticed Yukio had managed to sit in the chair at his desk, though slouching forward heavily, no doubt trying to keep pressure off of his aching rear end. His coat was back on, though it looked as if it had just sloppily been thrown over him.

“New rule..” The brunette breathed as he heard his brother approaching. “No more sex during school.”

The blunette chuckled and leaned into him from the side, curling his arms around the other’s shoulders to rub his back comfortingly.

“Yeah.. I guess that’s not unreasonable.”

They leaned against each other, again simply sharing a comfortable silence.

“Hey.. Yukio.”

“Hm?”

“… I love you, you know?”

The younger breathed out a soft sigh, smiling gently as he sat up a little to wrap his arms around Rin’s lower back, pulling him in and burying his face in his chest.

“Yeah… I love you too.”

The half demon smiled, wrapping his arms around his brother’s neck and pressing his face into that soft brown hair.

“Now.. help me up so we can go home please. My ass really hurts.” The brunette sighed.

“You just cursed.”

“Shut up Rin.”

**Author's Note:**

> Yukio looks good in thigh-highs.
> 
> Like..
> 
> REALLY good.


End file.
